(1) Field of the Invention
The present invention relates to an apparatus for compensating for such deformations as occur in first and second clamping surfaces intended for a tool in a press, the clamping surfaces being reciprocally moveable towards and away from one another for moving a first and a second part of the tool towards and away from each other, respectively, such deformations generating an uneven pressure in at least one area of contact between the tool and the clamping surfaces.
(2) Prior Art
In hydraulic presses, tools are positioned by means of which different objects are compression moulded to the desired configuration and appearance. Hydraulic presses operate at high pressure, which results in the parts in the hydraulic press, as well as the tool placed in the hydraulic press, being subjected to extreme stresses. These stresses are so great that the parts of the hydraulic press and the tool are deformed. This deformation results in the pressure distribution in those tools which are to impart to the final product its configuration and appearance becoming uneven. For example, the pressure will be lower in the centre of the tool and greater in its periphery. This will have as a result that the end product will be unevenly formed and will have an unacceptable quality.
In order to compensate for this deformation and distribute the pressure more evenly in presses, use has hitherto been made of shims, a form of interlay placed in between tools and the work surfaces of the hydraulic press. Cambering or crowning are also previously known methods for compensating for deformations. Cambering or crowning implies that those surfaces which are deformed during the pressing operation are arched so as to compensate for the deformation so that the compression pressure is distributed more evenly.
The drawbacks inherent in prior art technology are numerous. In the utilisation of shims, there is, granted, obtained a compensation for the deformation, but accurate setting is required and, this not withstanding, the compensation will be incomplete and above all not constant, but the compensation itself must be repeated at regular intervals. This results in unnecessary time loss for the compensation which lowers production capacity for the press. Another drawback inherent in shims is further that the thickness of the shims is given and not variable. Accuracy using shims is also difficult to achieve, which has a negative effect on the quality of the product produced using the tool in the press.
The drawback inherent in cambering or crowning is that the arching which is created is difficult to change in a simple manner if required. This lack of flexibility also results in considerable time loss when a new tool is to be positioned in a press. A cambering or crowning of the work surfaces of the press customised for the tool must then be utilised. Hence, cambering or crowning shows a low level of flexibility.
That which has hitherto been lacking in the art is an apparatus which is flexible and which can assume a thickness which fits a given situation in order to compensate for deformation in a press. In addition, there has been a lack of an apparatus which simply and rapidly can be adapted to a new tool disposed in a press. An apparatus for compensation of deformation which has a short adjustment time for a new tool and which thereby increases productivity in a press has long been sought for in the art. Further, a compensation apparatus which can compensate by bulging outwards has also been called for.